## Creating Time-Depth Chart for Deviated Well with known Average Velocity

I would be very happy if you could help me with one of the issues with IHS Kingdom, creating time depth charts for deviated wells.

I feel very confident in creating Time-Depth charts for vertical wells on Kingdom, either using checkshot data, or using some average velocities. Let me give you an example with avg velocities:

If I have 2 formations top met at 30 m and 40 m along a vertical well, with corresponding times t1 and t2 respectively, with an average velocity of 1000 m/s, then t1+((40-30)/1000)*2 gives me t2 in TWT, assuming constant velocity. For vertical wells measured depth (MD) is equal to True Vertical Depth (TVD). So the time depth chart is:

MD TVD Time

30m 30m t1

40m 40m t2

So, if we apply this to deviated wells:

If I have 2 formations top met at 30 m (t1) and 40 m (t2) along a deviated well, these values correspond to measured depths. If we have 60 degrees deviated wells from the vertical, then TVD correspond to 30*(cos60) and 40*(cos60), being 15m and 20m respectively (TVD). To calculate t2, with an average velocity of 1000 m/s, shall I:

T1+ ((40-30)/1000)*2 (eq1) or

T1+ ((20-15)/1000)*2 (eq2)

With Time-Depth chart to enter in IHS Kingdom:

MD TVD Time

30m 15m t1

40m 20m eq1 or eq2

Thank you very much in advance.

Don’t you have well deviation table with MD, TWT, Azimuth and Inclination informations in final well report?

How did you get avg velocity? do you have a average velocity volume? if so there is a neat function you can use.

Logs > Extract Log Curve Along Borehole…

Of course you are going to have to convert your velocities to depth first, but that is just depth converting them with themselves.

When you input the TD chart, make sure to have it set as TVD when you input it. Don’t try to do this by hand.

This is a pretty common operation for well planning.

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